Dataframe single-select and multi-select checkbox border not visible

Using the new dataframe select capabilities which put a checkbox as the first column in the dataframe. Unfortunately, the border color of an unselected checkbox is the same as the dataframe background. This makes it hard for a new user to understand that there is a checkbox in the first column. Many users click on a cell in the row expecting that to be a selection. The fix would be for the checkbox to have a default border background color that contrasted with the background of the dataframe.